Method of identifying a source component of particulate debris in an aircraft engine

ABSTRACT

The method can include analyzing the composition of the particulate metal debris, including ascertaining a presence of at least one main alloy element and a presence or absence of at least one signature alloy element in the particulate debris; establishing a correlation between the particulate metal debris and a set of components, including matching the ascertained presence of the at least one main alloy element to a family of alloys from which the components of the set, including the source component, are made; and determining the source component amongst the components of the set, including matching the ascertained presence or absence of the at least one signature alloy element to an alloy composition of the source component.

TECHNICAL FIELD

The application relates generally to maintenance and diagnostic ofaircraft engines and, more particularly, to a method of identifying asource component of particulate debris.

BACKGROUND OF THE ART

In aircraft engine, some components are designed to progressively wearduring engine operation and eventually be replaced. The presence ofparticulate material of such components in engine fluids can be normaland non-alarming. However, in some cases, the presence of particulatematerial in an engine fluid can be a sign of premature wear of acomponent or of another condition which should trigger enginemaintenance. By determining the nature of the debris (e.g. metal,carbon, polymer), one can obtain an indication of the nature of theengine condition, and can guide maintenance personnel in efficientlyperforming engine maintenance.

Even though known methods were satisfactory to a certain degree, thereremained room for improvement. In particular, there remained room forimprovement in further reducing the amount of maintenance time requiredfor a given engine.

SUMMARY

In one aspect, there is provided a method of identifying a sourcecomponent of particulate metal debris collected from an aircraft engine,the method comprising: analyzing the composition of the particulatemetal debris, including ascertaining a presence of at least one mainalloy element and a presence or absence of at least one signature alloyelement in the particulate debris; establishing a correlation betweenthe particulate metal debris and a set of components, including matchingthe ascertained presence of the at least one main alloy element to afamily of alloys from which the components of the set, including thesource component, are made; and determining the source component amongstthe components of the set, including matching the ascertained presenceor absence of the at least one signature alloy element to an alloycomposition of the source component.

In another aspect, there is provided a gas turbine engine comprising aset of components, the components of the set all being made of alloycompositions of the same alloy family having a common at least one mainalloy element, the alloy compositions having distinct signatures in theform of a varying trace amount of one or more signature element, thedistinct signatures varying from one component of the set to another.

In a further aspect, there is provided a method of identifying a sourcecomponent of particulate debris collected from a gas turbine engine, themethod comprising: analyzing the composition of the particulate debris,including ascertaining a presence of at least one main element and apresence or absence of at least one signature element in the particulatedebris; establishing a correlation between the particulate debris and aset of components, including matching the ascertained presence of the atleast one main element to a type of material composition from which thecomponents of the set, including the source component, are made; anddetermining the source component amongst the components of the set,including matching the ascertained presence or absence of the at leastone signature element to a material composition of the source component

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures in which:

FIG. 1 is a schematic cross-sectional view of a gas turbine engine;

FIG. 2 is a block diagram of a gas turbine engine;

FIG. 3 is a block diagram of a reference table, illustrating therelationship with the gas turbine engine of FIG. 2;

FIG. 4 is a flow chart of a method of determining a source componentfrom particulate debris;

FIG. 5 is a cross-sectional view of a gas turbine engine showing examplesets of alloy components;

FIG. 6 is a cross-sectional view of portions of a gas turbine engineshowing an example set of carbon seal components.

DETAILED DESCRIPTION

FIG. 1 illustrated a gas turbine engine 10 of a type preferably providedfor use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, acompressor section 14 for pressurizing the air, a combustor 16 in whichthe compressed air is mixed with fuel and ignited for generating anannular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases.

The compressor 14, fan 12 and turbine 18 have rotating components whichcan be mounted on one or more shafts. Bearings 20 are used to providesmooth relative rotation between a shaft and casing (non-rotatingcomponent), and/or between two shafts which rotate at different speeds.An oil lubrication system 22 including an oil pump 24, sometimesreferred to as a main pump, and a network of conduits and nozzles 26, isprovided to feed the bearings 20 with oil. Seals 28 are used to containthe oil. A scavenge system 30 having cavities 32, conduits 34, and oneor more scavenge pumps 36, is used to recover the oil, which can be inthe form of an oil foam at that stage, from the bearings 20.

Many gas turbine engines, such as the gas turbine engine 10 of FIG. 1,schematized in FIG. 2, include one or more sets of components 40, 42. Inone example, a gas turbine engine can include a plurality of bearingassemblies where each bearing assembly is positioned at a given axialposition and facilitates rotation and relative positioning at a rotaryinterface between a given combination of component portions. Bearingassemblies can include a plurality of sets of components. For instance,each bearing assembly can include a corresponding bearing cavity inwhich a corresponding bearing is enclosed, the bearing cavity beingterminated by corresponding seals. The plurality of seals associatedwith the different bearing assemblies of a given engine can be referredto as a set of seals, and the plurality of bearings can be referred toas a set of bearings. Typically, bearing cavities including seals andbearings are provided between rotary and non-rotary components, orbetween two components which rotate at a different speed (such as highpressure shaft and low pressure shaft), wherein the rotary componentsrotate around the engine's main axis. However, bearings and seals canalso be associated to components which rotate around axes different fromthe main axis, such as auxiliary shafts or power shafts of turboshaft orturboprop engines.

Many seals are made of carbon compositions, typically a compositematerial including a relatively high concentration of carbon in apolymer matrix. However, other sets of components can be configured toaccommodate potential rubbing between components which rotate relativeto one another. For instance, some gas turbine engines can have a set ofpolymeric materials, such as polymeric bushings, which are secured orotherwise integrated with non-rotary components, and are configured tobe occasionally rubbed against by rotating components in certain engineoperation conditions. Even in the case of rotary interfaces betweencomponents, some seals are directly made of metal alloys rather thanmaking use of composite materials.

Some gas turbine engines can also include one or more sets of rotatingcomponents such as gears, shafts, or the like. Such rotating componentsare typically made of metals, and in the field of aerospace/aeronautics,much consideration can be given to the exact choice of alloy to optimizethe materials for corresponding functions and for correspondingcontexts.

Many contact interfaces between relatively moving components, such asbetween rotary and non-rotary components, between components that rotateat different speeds, or components which may otherwise occasionally rubagainst one another, have wearable components, i.e. components which aredesign to wear over time due to rubbing, abrasion, or the like.Typically, wearable components are designed to wear more easily than acomponent which is rubbed against it, in a sacrificial manner, meaningthat the wear component is designed to be changed once it has worn by acertain amount, whereas the condition of the component which has rubbedagainst it has been preserved throughout the wear. Wear components caninclude carbon seals and polymer bushings, for instance, but can alsoinclude some alloys.

Many contact interfaces are exposed to a recirculated lubrication fluidsuch as oil, in a manner to lubricate the components and limit wear. Inthe case of gas turbine engines, as new oil gradually replacespreviously sprayed oil, the previously sprayed oil is eventuallygathered by the bearing cavity, scavenged, and circulated across afilter and air/oil separator, and recycled as new oil. Particles ofvarious components at the interfaces can thus be collected by the oil,and eventually captured by a filter or the like, or collected in an oilreservoir. Scavenged particle analysis can be performed on suchcaptured/collected particles. Using basic equipment, such as amicroscope for instance, it is typically relatively easy to distinguishbetween entirely different materials, such as between carbon, polymer,and even different alloys such as steel and Inconel. However, scavengedparticle analysis can be pushed further, typically using more elaboratedequipment, and even determine the composition of scavenged particles.While some wear components are expected to wear at a certain rate,scavenged particle analysis may also allow to detect the presence ofparticles associated with components which are not supposed to wear, oreven establish an abnormal quantity of particles of a component which isexpected to wear. Such detections can be indicative of premature wear ofa component, or even engine malfunction, and may trigger a furtherinvestigation and associated engine maintenance.

The analysis of the detected particles may not allow to single out agiven component, from a set of components, which causes the issue. Forinstance, the particle analysis may allow to establish that there is apremature wear of a carbon seal, while not allowing to single out whichcarbon seal, amongst the set of carbon seals of a given engine, is beingsubjected to premature wear. The same can be said about differentinterface portions of shaft(s) from a set of engine components made of asimilar alloy, or different polymer bushings from a set of polymerbushings, for instance. The maintenance personnel therefore has arelatively large field of investigation, and may require a significantamount of maintenance time, and disassembly of a large amount ofcomponents, before being able to conclusively establish the source ofthe premature wear. Since maintenance time has a direct relationshipwith maintenance costs, there was a need to reduce the amount ofmaintenance time, and accordingly, there can be a need to allowmaintenance personnel to obtain more information about the identity ofthe component which is the source of the identified problem or concern,in a manner to narrow the field of investigation of maintenancepersonnel, and ultimately reduce maintenance time.

For instance, if a carbon seal starts to spin and rub against its statichousing, maintenance personnel may appreciate receiving an indicationthat the debris stems from carbon rubbing against its housing as opposedto carbon rubbing against a turning shaft. Further receiving anindication of which carbon seal is so behaving may even further assistmaintenance personnel in focusing their maintenance time on the correctseal, instead of disassembling a larger number of components to access alarger number of seals for visual inspection.

Henceforth, in accordance with one aspect, there is provided a gasturbine engine having a set of components associated with correspondinginterfaces between rotary and non-rotary components and/or betweencomponents rotating at different speeds, wherein the individualcomponents of the set are made of the same type, or family, of material(e.g. carbon composite, polymer, given alloy type), but where the exactmaterial composition of each component of the set differs discernably,even though slightly, from the material of the other components of theset. More specifically, each component of the set can be made of amaterial composition having a unique signature amongst the components ofthe set. The distinct signature can be in the form of a varying traceamount of one or more elements which may be present in such lowquantities so as to have no significant effect on the materialproperties of the set, while still being present in a sufficientconcentration so as to allow distinguishing its presence from animpurity.

The difference can be in the form of the presence of different traceelements, different concentrations of a given trace element, differentcombinations and/or concentrations of trace elements, to name someexamples. The concentration of the trace element(s) can be selected in amanner to be sufficient to allow to detect it, or to allow todifferentiate the relative concentrations of the trace element indifferent components of the set, while not being sufficient tosignificantly affect the functionality of the component. The traceelement can thus be used specifically for the purpose of traceability asto the source component from a set of components of eventual particleswhich are collected, such as particles collected by the scavenge systemfor instance.

Accordingly, once the particles have been collected, they can beanalyzed so as to characterize their composition, yielding a list ofdistinct elements forming the composition, and possibly even aconcentration of such elements in the composition of the particulatedebris. Some of the elements can be main elements of a given materialfamily, or otherwise said, the basic ingredients forming thecorresponding type of material composition. For instance, stainlesssteel is known to include an important concentration of Fe, whereascarbon composites of carbon seals are known to include importantconcentrations of carbon. One or more other elements, referred to hereinas signature elements, can be introduced, or their concentrationsmodulated, in a manner to form slight but measurable distinctionsbetween the different components of the set. For instance, varyingconcentrations of tin or lead can be added to different ones of thecarbon seals, or varying concentrations of gold, silver and/or platinumcan be added to different ones of the carbon seal housings, or todifferent ones of the gears, for instance. The expression “element” isused herein for the sake of simplicity, and it will be understood thatthe main elements and the signature elements can be in the form ofmolecules instead of atoms in some cases.

Referring to FIG. 3, each component of the set can become encoded with aspecific presence, absence, or proportion of one or more signatureelement. This coding can be preserved once the components of the setsare assembled into the aircraft engine. For instance, the carbon sealsof the #1 bearing can be components 1 and 2, the carbon seals of the #2bearing can be components 3 and 4, and so forth, and each of thecomponents 1 to n can have a specific “component definition” 44 allowingto determine its signature upon analysis of particulate debristherefrom. The definition for a given component may be the detailedcomposition, or may be simplified in a manner to contain only acombination of elements, and may additionally specify thresholdconcentrations for such elements. The definitions can be stored in theform of a reference table 46 which can be printed on paper, or stored asdata in a computer readable memory, to name two examples.

In some cases, such as in an embodiment where one is only interested incarbon seals for instance, it may be easy to differentiate particulatedebris stemming from carbon seals from particulate debris stemming fromother engine components, and therefore ascertaining the set ofcomponents may be straightforward, and the challenge will only lie indetermining which one of the components of the set is the source of thedebris. In other cases, one may be interested in tracking debris frommore than one set of components on a given engine, and a preliminarystep of determining which set of components the particular particulatedebris comes from may be required before being able to identify whichone of the components of that set is the source of the particulatedebris. To this ends, different sets can be attributed different “setdefinitions” 48 allowing to distinguish, in a given aircraft engine,which “set of components” the debris is attributable to. The setdefinitions can be more or less elaborated depending on the application.Generally, the set definitions will typically include the identificationof one or more main element of the type of material composition family(e.g. Fe, C, a polymer string, etc). In some embodiments, the setdefinitions can additionally specify threshold concentrations for one ormore main element detected. Similarly to the component definitions, theset definitions can be stored in the form of a reference table which canbe printed on paper, or stored as data in a computer readable memory, toname two examples.

The definitions may not be exhaustive in some embodiments, and simplydefine a minimum threshold concentration value (e.g. to ascertain apresence), a maximum threshold concentration value, both a minimum and amaximum threshold values defining a range. In some embodiments, byhaving a signature element on top of a general proportion, the detectionsystem can release certainty threshold about a particular alloy. Sobefore the detected proportions of a certain stainless steel elementsmatch the detection criteria (ex.: 2-3% Ni, 6-15% Cr, >50% Fe), as longas the signature element is detected along with the other ones, thepresence of that specific alloy can be confirmed. In that case, there isno need to match proportion before being sure about the presence of analloy. Typically, the definition will include at least a nature of anelement, and optionally a concentration range or threshold for thatelement.

In alternate embodiments, the component definitions may be sufficientlyexhaustive by themselves to allow to perform a complete segregation ofthe components from one another without having to perform a priorsegregation between sets of components, for example.

Accordingly, with reference to FIG. 4, once particulate debris collected50 from an aircraft engine has been analyzed 52, the presence of atleast one main element, and a presence or absence of at least onesignature alloy element have been ascertained, a correlation can beestablished between the particulate debris and a specific set ofcomponents 54, and further between the particulate debris and a specificone of the components of the set 56. For instance, the correlationbetween the particulate debris and the set of components can beestablished on the basis of matching the detected presence of the one ormore main alloy element with a corresponding set definition. Thecorrelation with the specific component of the set as being the sourcecomponent can be established on the basis of matching the detectedpresence or absence of the signature element with a correspondingcomponent definition. In some embodiments, the correlations and matchescan be established by a computer which is provided access to the dataconcerning the elements which were detected in the particulate debris,and the definitions, and the computer generates a signal indicative ofan individual component within the set 58, whereas in other embodiments,the correlation and matching can be made by maintenance personnel.

In some embodiments, rather than just ascertaining a presence or absenceof a given element, it can be considered useful to measure theconcentration of the given element, and to compare it to a correspondingthreshold included in the corresponding definition, in a manner to allowmaking the determination.

The collection of the particulate debris can be performed in variousways and the exact choice can depend on the specificities of the givenapplication. For instance, particulate debris can be present in the formof dust on a solid surface and can be collected directly from thesurface, it can be present in a fluid of the engine, such as the oil forinstance, and the oil itself can be collected and analyzed. Moreover,some engines use magnetic chip collectors in the oil flow, and themagnetic field of such chip collectors can maintain chips attracted evenwhen the engine has stopped. And to name another example, particulatedebris can be collected directly from an oil filter.

Some examples will now be presented for additional clarity.

Alloy Example

A fleet can be managed by trend monitoring engine condition. Forinstance, trend monitoring can be performed to plan maintenanceactivities and/or prevent failures by detecting early signs ofwear/failures. Such monitoring can be done by analyzing the nature ofoil particle content or filter debris.

In order to be able to trace the source of failures and/or monitorengine/component condition, the alloying content of a recurring mainalloy can be varied from one component to another in a manner for itspresence to be detectable.

This can be done by adding specific element to the alloy formula (asshown in example below) to a level that doesn't interfere with itsphysical or mechanical properties while still being detectable.

Example of Alloys Modulation:

AMS6000 contains: Fe 10%, Ni 20%, Cr 70%

AMS6000B contains: Fe 10%, Ni 20%, Cr 70%, signature element #1 0.1-0.2%

AMS6000C contains: Fe 10%, Ni 20%, Cr 70%, signature element #2 0.3-0.4%

Wear rate or failure events can become traceable and components can besegregated from one another.

This can be coupled with trend a monitoring system (e.g. oil analysis,chip analysis, debris filter analysis or other) and data analysis.

To the extreme, every single part of the engine could be made out ofslightly different alloys (x modulations of main alloys). When an eventoccurs, precise knowledge of affected components and even sequence ofevent could be understood based on dust collection analysis or oilcontent analysis.

Every component can be made of an alloy having a single signature.

In some more limited examples, alloy modulation can be applied to setsof gears (AGB gears, RGB gears), sets of bearings (RGB, main shafts),sets of seals (main shaft seals, AGB seals) or sets of other parts forwhich progressive failure might occur.

FIG. 5 shows an example where sets of gears 62, 64, and sets of bearings66 which can be made out of alloy modulations.

For instance, every gear of the same gear train can be made of similarsteel with slight signature element modulation, allowing detecting whichone is failing/wearing. For smaller sets, this can represent less than10 variations of the same alloy.

The gold lots can be identified in this manner (alloying elements addedin low quantities) to trace their origins. The segregation of alloy canbe done for trend monitoring purpose and/or failure event understanding.

Instead of adding different elements, different proportions of the sameadded element can be added to the alloy to get low but detectablephysical/mechanical properties variations.

Carbon Example

Carbon seals on turbine engine generally wears and their conditionaffects engine performance.

Carbon is generally used for its favorable friction behavior to sealrotating interfaces. The carbon elements are generally placed between arotating surface and a static structure holding it in place. The facethat touches or at risk of touching the rotating surface is subject towear. There is a need and a general desire to closely monitor wearand/or wear rate and/or seal condition through the life of the engine inorder to ease maintenance and/or prevent failures. Detection methods andbig data/trend monitoring systems can be used as fleet managementmethods. FIG. 6 shows three carbon seals which can have components 70,72, 74, 76 made of different carbon compositions. Sealing surfaceconfigurations can be radial or axial.

In order to be able to trace the source of failures and/or monitorindividual seal condition, the material content of a recurring maincarbon grade can be varied in a detectable manner.

This can be done by adding a specific element to carbon compositionformula (as shown in example below). The amount of added element may beinsufficient to significantly affect the performance of the seal(physical or mechanical properties) while being sufficient to bedetectable. The signature element can have uniqueness to more clearlydistinguish from standardized materials already used in the productionprocess.

Example of Carbon Composite Modulation:

Carbon #1 contains: C 80%, O 18%, Ca 1%

Carbon #1B contains: C 80%, O 18%, Ca 1%, other element #1 0.1-0.3%

Carbon #1C contains: C 80%, O 18%, Ca 1%, other element #2 0.4-0.5%

Wear rate or failure events can thus be traceable and components can besegregated from one another. This can be coupled with trend monitoringsystems (oil analysis or others) and data analysis activities.

This can be done in phase with debris monitoring systems being deployedon latest engine programs. This would allow to prevent failures or planmaintenance activities.

As prior art, the gold lots can be identified in this manner (alloyingelements added in low quantities) to trace their origins. In the case ofthis disclosure, the segregation of alloy would be done for trendmonitoring purpose and/or failure event understanding.

Every seal is made of a carbon having a single signature. Instead ofvarious elements, it could be various proportions of the same addedelement or working on the composition to get low but detectablephysical/mechanical properties variations (radioactivity, electrical,magnetism).

The same concept could be applied to another material with favorablefrictional properties.

ALTERNATE EMBODIMENTS

It will be understood that in some embodiments, the set of componentscan include a plurality of components having the same function in thegas turbine engine, but located at different positions in the gasturbine engine. More specifically, the different components of the setcan be located at corresponding contact interfaces, such as rotaryinterfaces where the component can come into contact with anothercomponent of the aircraft engine. The components of the set can becomponents which have different functions, but which are made of thesame type of alloy for instance. The components of a given set can beone or more of a shaft, a bearing, a gear, and a shaft mounted feature.In other embodiments, all the components can be of the samefunctionality, such as all being part of a shaft, all being gears, allbeing bearings, for instance.

In the case of sets of components all made of a given alloy family, thealloy family can be steel, stainless steel, nickel, titanium, aluminum,to name some examples, and in which case the signature element can beone or more of gold, silver, tungsten and platinum to name some possibleexamples.

In the case of sets of components all made from a given family of carbonmaterials, the carbon material can be a composite including carbonparticles in a polymer matrix for instance, and the signature elementcan be one or more of tin and led for instance.

In the case of sets of components all made from a given family ofmechanical polymers, the mechanical polymer can be PEEK, Polyketone,Polyamid or Polyimid for instance, and the signature element can be oneor more of tin and led for instance, or any other suitable detectablematerial

The proportion of the signature element can vary in differentembodiments. It can be preferred in some embodiments to keep theconcentration low to avoid a scenario where adding the tracing abilitywould interfere with the material's mechanical or physical properties.For instance, in some cases, it can be preferred to keep theconcentration of the signature element below 3% by weight, preferablybelow 1% by weight, and more preferably below 0.5% by weight. On theother hand, it is known in the production of alloys, mechanical polymersand carbon materials that some level of impurities can be considerednormal and acceptable, and it may be preferred to maintain theconcentration of the signature element above such an impurity thresholdto allow to differentiate the signature element from an impurity. Tothis end, it can be preferred to maintain the concentration of thesignature element above 0.01% or above 0.02% for instance.

The embodiments described in this document provide non-limiting examplesof possible implementations of the present technology. Upon review ofthe present disclosure, a person of ordinary skill in the art willrecognize that changes may be made to the embodiments described hereinwithout departing from the scope of the present technology. Yet furthermodifications could be implemented by a person of ordinary skill in theart in view of the present disclosure, which modifications would bewithin the scope of the present technology.

1. A method of identifying a source component of particulate metaldebris collected from an aircraft engine, the method comprising:analyzing the composition of the particulate metal debris, includingascertaining a presence of at least one main alloy element and apresence or absence of at least one signature alloy element in theparticulate debris; establishing a correlation between the particulatemetal debris and a set of components, including matching the ascertainedpresence of the at least one main alloy element to a family of alloysfrom which the components of the set, including the source component,are made; and determining the source component amongst the components ofthe set, including matching the ascertained presence or absence of theat least one signature alloy element to an alloy composition of thesource component.
 2. The method of claim 1 wherein the steps ofestablishing and determining are performed by a computer, furthercomprising the computer generating a signal indicating the identity ofthe source component.
 3. The method of claim 1 wherein the analysing thecomposition includes measuring a concentration of the at least one mainalloy element in the particle metal debris, and wherein the step ofmatching the ascertained presence of the at least one main alloy elementincludes comparing the measured concentration to at least one thresholdvalue associated with a definition of the family of alloys.
 4. Themethod of claim 1 wherein the analyzing the composition includesmeasuring a concentration of the at least one signature alloy element inthe particle metal debris, and wherein the step of matching theascertained presence or absence of the at least one signature alloyelement includes comparing the measured concentration to at least onethreshold value associated with a definition of the of the sourcecomponent alloy composition.
 5. The method of claim 1 further comprisingcollecting the particulate metal debris from the aircraft engine.
 6. Themethod of claim 5 wherein the particulate metal debris is collected bycollecting dust from the aircraft engine.
 7. The method of claim 5wherein the particulate metal debris is collected by a chip collector ofthe aircraft engine.
 8. The method of claim 5 wherein the particulatemetal debris is collected from a filter of the aircraft engine.
 9. Themethod of claim 1 wherein the analyzing includes performing oil analysisof oil from the aircraft engine.
 10. A gas turbine engine comprising aset of components, the components of the set all being made of alloycompositions of the same alloy family having a common at least one mainalloy element, the alloy compositions having distinct signatures in theform of a varying trace amount of one or more signature element, thedistinct signatures varying from one component of the set to another.11. The gas turbine engine of claim 10 wherein the set of componentsincludes a plurality of components having the same function in the gasturbine engine, but located at different positions in the gas turbineengine.
 12. The gas turbine engine of claim 10 wherein the components ofthe set are located at respective contact interfaces of the gas turbineengine.
 13. The gas turbine engine of claim 12 wherein the contactinterfaces are rotary interfaces where corresponding components can comeinto rubbing rotary contact with another.
 14. The gas turbine engine ofclaim 10 wherein each component of the set is one of a shaft, a bearing,a gear, and a shaft mounted feature.
 15. The gas turbine engine of claim10 wherein all components of the set are one of shafts, bearings,accessory gears, and power gears.
 16. The gas turbine engine of claim 10wherein the alloy family is one of steel, stainless steel, nickel alloy,titanium alloy, aluminum alloy.
 17. The gas turbine engine of claim 10wherein the one or more signature element is selected from the groupconsisting of gold, silver, tungsten and platinum.
 18. The gas turbineengine of claim 10 wherein the trace amount is of between 0.01% and 3%by weight.
 19. The gas turbine engine of claim 10 wherein the traceamount is a weight percentage value which is above an impuritythreshold, and below a material property alteration threshold for thecorresponding signature element in the alloy type.
 20. A method ofidentifying a source component of particulate debris collected from agas turbine engine, the method comprising: analyzing the composition ofthe particulate debris, including ascertaining a presence of at leastone main element and a presence or absence of at least one signatureelement in the particulate debris; establishing a correlation betweenthe particulate debris and a set of components, including matching theascertained presence of the at least one main element to a type ofmaterial composition from which the components of the set, including thesource component, are made; and determining the source component amongstthe components of the set, including matching the ascertained presenceor absence of the at least one signature element to a materialcomposition of the source component.